Title:
RECIPROCATING PLUNGER TYPE FUEL INJECTION PUMP HAVING ELECTROMAGNETICALLY OPERATED CONTROL PORT
United States Patent 3779225
Abstract:
A fuel injection system for an internal combustion engine of the type having a reciprocating piston pressure pump that includes an electromechanically operated relief or control valve that is arranged so that the face of the valve is not subjected to the pressurized fluid in the pumping chamber, thereby requiring less electromechanical energy to open and close the valve. In this type of arrangement it is now possible to control the opening and closing of the relief valve independently of the reciprocating motion of the piston which pressurizes the fuel in timed relation to rotation of the camshaft or crankshaft of an internal combustion engine.
US Patent References:
Fuel-feeding system
French - April 1928 - 1664610
Fuel injecting device for internal combustion engines
Planiol - April 1937 - 2077259
Fuel injection apparatus
French - May 1952 - 2598528
Fuel injection devices for multicylinder engines
Bessiere - December 1958 - 2863437
High pressure fuel injection apparatus for internal combustion engines
Asaka et al. - June 1965 - 3191812
Fuel-feeding system
French - April 1928 - 1664610
Fuel injecting device for internal combustion engines
Planiol - April 1937 - 2077259
Fuel injection apparatus
French - May 1952 - 2598528
Fuel injection devices for multicylinder engines
Bessiere - December 1958 - 2863437
High pressure fuel injection apparatus for internal combustion engines
Asaka et al. - June 1965 - 3191812
Inventors:
Watson, Edwin B. (Sidney, NY)
Fuller, Harlan I. (Doylestown, PA)
Fuller, Harlan I. (Doylestown, PA)
Application Number:
05/260882
Publication Date:
12/18/1973
Filing Date:
06/08/1972
View Patent Images:
Export Citation:
Assignee:
The Bendix Corporation (Southfield, MI)
Primary Class:
Other Classes:
123/472, 123/458
International Classes:
F02M59/36; F02M59/20; F02D5/00
Field of Search:
123/139E,139AM,139AK,32AE,32EA
US Patent References:
| 3417703 | Fuel injection pump | December 1968 | Eckert et al. |
Primary Examiner:
Goodridge, Laurence M.
Assistant Examiner:
Flint, Cort
Claims:
Having described the invention, what is claimed is
1. A pump for supplying pressurized fluid which comprises:
2. The pump as recited in claim 1 wherein said means for pressurizing fluid in said pumping chamber comprises:
3. The pump as recited in claim 2 wherein said solenoid core is mounted transverse to said pump piston.
4. The pump as recited in claim 1 wherein said solenoid core is mounted transverse to a wall of said pumping chamber so that said plunger extends into said chamber through said relief port.
5. The pump as recited in claim 2 wherein said solenoid core is mounted transverse to a wall of said pumping chamber so that said plunger extends into said chamber through said relief port.
6. A fuel injection system for an internal combustion engine of the type having a cam shaft, the system comprising:
1. A pump for supplying pressurized fluid which comprises:
2. The pump as recited in claim 1 wherein said means for pressurizing fluid in said pumping chamber comprises:
3. The pump as recited in claim 2 wherein said solenoid core is mounted transverse to said pump piston.
4. The pump as recited in claim 1 wherein said solenoid core is mounted transverse to a wall of said pumping chamber so that said plunger extends into said chamber through said relief port.
5. The pump as recited in claim 2 wherein said solenoid core is mounted transverse to a wall of said pumping chamber so that said plunger extends into said chamber through said relief port.
6. A fuel injection system for an internal combustion engine of the type having a cam shaft, the system comprising:
Description:
BACKGROUND OF THE INVENTION
This invention relates to an internal combustion engine fuel injection system of the type having a source of fuel, a fuel pump for pressurizing the fuel, and one or more injectors or nozzle assemblies for injecting fuel into the engine cylinders. The invention is more particularly related to an improved pump of the type having a reciprocating piston for pressurizing fluid and a solenoid-operated control valve for controlling the amount of fluid dispensed by the pump.
Mechanical fuel injection systems for internal combustion engines generally include a fuel tank; the fuel pump that receives fuel from the tank and pressurizes the fuel; and one or more nozzle valve assemblies that receive the pressurized fuel and inject it into the engine cylinder. The fuel pump which pressurizes the fuel to be supplied to the engine cylinders may be of the rotary or reciprocating piston or plunger type. An example of a rotary injection fuel pump may be found in U.S. Pat. No. 3,489,091 entitled "Rotary Distributor Pump," issued Jan. 13, 1970 to P. Becker. Examples of fuel injection pumps that operate on the principle of a reciprocating piston or plunger may be found in U.S. Pat. Nos. 2,922,581 entitled "Fuel Injection Apparatus", issued Jan. 26, 1960 to L. J. Garday; 3,146,715 entitled "Fuel Injection Pump," issued Sept. 1, 1964 to G. J. Knudson; and 3,190,561 entitled "Fuel Injector," issued June 22, 1965 to H. I. Fuller et al.
Fuel pumps of the reciprocating piston type generally include a housing; a piston mounted for reciprocating movement within the housing, the piston cooperatively linked to the crankshaft or camshaft of an internal combustion engine so that rotation of the camshaft causes reciprocation of the piston within the pump housing; and a pressure chamber, one wall of which is the face of the reciprocating piston, the pressure chamber having an inlet port, a relief (bypass) port and an injection port. In all of the reciprocating type pumps the piston includes a passageway (generally a groove or passage in the piston) that periodically links the pressure chamber to the relief port during the stroke of the piston. The shape and arrangement of the passage and the piston are designed so that radial adjustment of the piston (by rotating the piston) from one position to another affects the periodic linking of the relief port to the pressure chamber, thereby controlling injection time and hence the volume of fuel injected into an engine cylinder. Therefore, the quantity of fuel injected into the engine is determined by radially adjusting (rotating) the reciprocating pistons which are mechanically linked to the camshaft of the engine. Because the piston is mechanically linked to the camshaft, the point in time at which fuel is injected into the engine cylinders is generally fixed with respect to the degree of rotation of the camshaft from a common reference point.
Another limitation and disadvantage associated with fuel pumps of the reciprocating piston type is that the reciprocating piston determines the beginning of the injection cycle, i.e., the piston starts the beginning of the injection cycle when it closes the inlet port and the piston begins to build up pressure in the pressure chamber until the pressure reaches a point that causes the injection port to be opened and fuel to be injected into the engine cylinder. In most systems, once a reciprocating fuel pump is installed, the reciprocating piston is mechanically linked to the engine camshaft or crankshaft so that the inlet port always closes when the camshaft reaches the same degree of rotation. A common approach of making the closing of the inlet port vary with respect to the degree of rotation of the camshaft is to introduce a mechanical translator between the engine camshaft and the pump piston. However, mechanical translators (timing advance mechanisms) are both bulky and expensive, which of course is undesirable for commercial fuel injection systems. Another solution to the problem was to eliminate the reciprocating piston and employ a solenoid-operated injector which is electronically controlled by sophisticated switching circuitry. However, this type of system requires an extremely high pressure pump, more expensive electromechanical and electrical components, and very complex injectors.
Therefore, to control the amount of fuel injected into an internal combustion engine over a wide range of engine speeds, inventors have attempted to modify the fuel pump of the reciprocating piston type in a manner so as to control the inlet port opening and closing. Having failed to do this in an economical and practical way, the art has turned toward electronic fuel injection systems which do not employ a fuel pump of the reciprocating piston type and which are relatively expensive and complex.
SUMMARY OF THE INVENTION
This invention provides a mechanical fuel injection control system that utilizes a reciprocating piston type fuel pump that is capable of varying the amount of fuel injected into the engine cylinder at fixed and/or at different speeds of rotation of the engine cam and/or crank-shaft.
The invention is a fuel injection pump for an internal combustion engine characterized by an electromechanically operated control or relief valve assembly (27) that is controlled independently of a reciprocating piston (31) in the pump that pressurizes the fluid. The invention is also characterized by an electromechanical relief (control) valve (20) that has a valve face (23) that is not subject to the pressure in a pressure chamber so that the valve requires less electromechanical energy to open and close.
In one embodiment of the invention the fuel injection system for an internal combustion engine of the type having a camshaft comprises: a pump housing (1) having a pressure chamber (10) that communicates with an inlet passage (6), a relief passage (3) and an injection passage (15), the injection passage communicating with the engine; means for supplying fuel to the pumping chamber through said inlet passage; means for closing the injection passage (15), the closing means including biasing means (52), for keeping the injection passage closed until a predetermined fuel pressure is attained in the pumping chamber; means (30) responsive to the rotation of the engine camshaft or crankshaft for periodically pressurizing the fuel in the chamber (10) whereby fuel entering the chamber through the inlet passage periodically flows out of the pumping chamber through the relief (bypass) passage; and electro-mechanical valves means (27) operative to open and close the relief passage (3) at predetermined intervals in response to at least one operating parameter of the engine whereby each time the relief (bypass) passage (3) is closed and fuel is being pressurized, the fuel pressure in the pumping chamber attains a predetermined pressure level at which the injection passage is opened, thereby injecting fuel into the engine. This type of pump assembly makes it possible to open and close the relief passage independently of the reciprocating motion of the plunger 31.
Accordingly, it is an object of this invention to provide a fuel injection pump of a reciprocating piston type wherein the control of the relief valve is independent of the reciprocating piston.
It is another object of this invention to provide a control valve assembly for the relief (bypass) port of the pressure chamber wherein the axial movement of the valve is not biased by pressurized fluid within the pumping chamber.
It is still another object of this invention to eliminate the need for bulky and expensive mechanical timing devices between an internal combustion engine and a fuel injection pump.
It is yet another object of this invention to provide a control valve for a pressure chamber that permits a maximum flow rate to be obtained over a minimum amount of valve travel.
It is still another object of this invention to combine a novel means to control the amount and duration of fuel delivery with a fuel pump of known characteristics, thereby improving the versatility of fuel injector pumps of the reciprocating piston type.
It is also an object of this invention to provide a means for controlling fuel quantity and timing by utilizing a solenoid-operated control valve responding to one or more engine parameters.
The above and other objects and features of the invention wlll become apparent from the following detailed description taken in conjunction with the accompanying drawings and claims which form a part of this specification.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a fuel pump for an internal combustion engine that incorporates the principles of this invention.
FIG. 2 is an enlarged partial diagrammatic view showing the valve portion of the solenoid and the reciprocating plunger.
FIG. 3 is a diagrammatic top view of the pressure chamber taken along lines III--III in FIG. 2.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to the drawings, FIG. 1 illustrates a fuel injection pump 1 of the type having a reciprocating piston assembly 30 for pressurizing the fuel in response to rotation of an internal combustion engine (not shown), a solenoid-operated relief or control valve assembly 27 that is controlled independently of the reciprocating piston assembly 30, and an injection or delivery valve assembly 50 that communicates with the engine cylinder.
The reciprocating piston assembly 30 comprises: a can follower 32 that follows the camshaft or crankshaft of an internal combustion engine (not shown); a spring assembly 33 which maintains the cam follower 32 in contact with the camshaft; and a piston 31 which reciprocates in the bore of housing 60.
The electromegnetic valve assembly 27 comprises: a coil of wire 24 which receives power from a source (not shown); and a valve or solenoid core 20 which is axially movable in response to energization of the coil 24. Spring 28 biases valve 20 axially in the open position so that energization of the solenoid coil 24 is required to close the valve 20. The movable valve 20 includes a hollow portion 21, the purpose of which is to decrease the mass of the core so that less electromagnetic energy is required to move the valve 20. The valve 20 includes an end face 23 which terminates within the housing 60. An important feature of the valve 20 is the annular groove 2 therein which links relief passage 3 with the bore 10 in the housing 60 when the valve 20 is extended to its farthest position from the coil 24. Obviously, portions of the core 20 not required to be responsive to the solenoid can be fabricated from materials other than iron.
The pump assembly 1 further includes a source or supply chamber 5 which supplies fuel to a pressure chamber 10 through (inlet) passage 6. The supply chamber 5 also communicates with the pressure chamber 10 through (relief) passage 3 and the passage formed by the annular groove 2 of the valve 20 when the valve 20 is in the position shown.
In the FIGURE shown, passage 6 is closed because of the position of piston 31 and the relief passage 3 is open because of the position of the solenoid valve 20. Therefore, the inlet passage 6 of the pressure chamber 10 is closed and the relief passage 3 is open, preventing pressurizing of the fuel in chamber 10 by the piston 31.
The fuel injection pump 1 further includes an injection valve assembly 50 which includes: a delivery valve 51; a valve seat 49 for receiving valve 51; a spring assembly 52 for maintaining the valve 51 in a closed position until a predetermined pressure is attained in chamber 10, the valve 51 and valve seat 49 being disposed in a chamber 15 that communicates with passages 56 and 57 that lead to the engine cylinder. The valve 51 is shown in the closed position which prevents fuel in pressure chamber 10 from communicating with the fluid in chamber 15 and thereby injecting fuel into the engine. The valve 51 is biased closed by spring 52 so that valve 51 does not open until the pressure in the passage 10 reaches a predetermined pressure level which is much greater than any pressure level of the fluid in the supply chamber 5. FIG. 1 illustrates the pressurizing piston 31 at the top of its stroke and the solenoid valve positioned so that the pumping chamber 10 communicates with the supply chamber 5 through passage 3 so that the pressure in chamber 10 is not appreciably greater than the pressure within the supply chamber 5.
FIG. 2 is an enlarged cross-sectional diagrammatic view of the pump assembly shown in FIG. 1. In this diagrammatic view the supply chamber 5 communicates with the pressure chamber 10 only through the inlet passage 6 because the iron core 20 of the solenoid valve has been moved to a position to block the relief passage 3 that would otherwise communicate with the pressure chamber 10. This diagrammatic view illustrates that as piston 31 rises to point A, it closes the inlet port connected to the supply chamber 5, thereby allowing the fuel in the chamber 10 to be pressurized as the volume of the chamber decreases. When the pressure of the fluid in chamber 10 reaches a predetermined pressure value, valve 51 (FIG. 1) opens, allowing fluid to flow around the valve body 20 through the injector valve assembly (50, FIG. 1) and to the internal combustion engine (not shown). Another feature of the invention which can be seen in FIG. 2 is the fact that the face 23 of the valve 20 is not subject to the pressure in chamber 10. If the electromagnetic valve face 23 terminated within chamber 10, it would be subject to pressures that would require additional electromagnetic force to move the valve body 20. Further, since the movement of the valve 20 is independent of the operation of the reciprocating piston 31, control and injection of fuel into an engine cylinder may be started and stopped at any point in time regardless of the angle of rotation of the camshaft. This is an important feature of this invention in that prior art reciprocating type fuel injection pumps were not capable of obtaining this feature.
FIG. 3 is a diagrammatic view looking into pressure chamber 10 along lines III--III in FIG. 2. This FIGURE illustrates the shape of the pressure chamber 10 that allows pressurized fluid to flow around the valve body 20. The valve body 20 is shown in the open position so that fluid in the pressure chamber 10 may flow through the bypass or relief passage 3 to the supply chamber 5. This view further illustrates how axial movement of the valve 20 in an axial direction opens and closes the communicating link between the pressure chamber 10 and the bypass passage 3. This FIGURE further illustrates that the face of the valve 20 is not at any time located within the pressure chamber 10 and therefore is not subjected to any axial forces caused by the fluid in the chamber when the valve 20 is closed or open. Movement of the body 20 in either axial direction is in the order of .005 inches or less, allowing a maximum flow rate to be obtained in a minimum amount of time.
OPERATION
Referring now to the drawings, and more particularly to FIGS. 1 and 2, the fuel pump 1 operates as follows: a sensing device (not shown) senses one of the operating parameters of the internal combustion engine (not shown) to control the axial movement of the solenoid core or valve 20. The control signal has the effect of causing the body 20 to oscillate at various magnitudes and/or frequencies. Simultaneously with the movement of the iron core 20, the piston 31 reciprocates in response to the action of the spring 33 and cam follower 32 which is following the rotating camshaft of the internal combustion engine. Once the piston 31 has risen to a point in the bore of the housing 60 past the passage 6, fluid in the chamber 10 will or will not be pressurized, depending upon the location of the iron core 20. If the iron core 20 is in the position shown in FIG. 2, there is no communicating link between the chamber 10 and the supply chamber 5, as the location of annular groove 22 is such that passageway 3 does not communicate with pressure chamber 10. Therefore, pressure in the chamber 10 will increase until the delivery valve 51 opens, allowing fuel to pass through passage 57 and to the engine cylinder. Fuel will continue to flow through passage 57 until either the relief port opens or the piston 31 reverses direction, which increases the volume of chamber 10, decreasing the pressure in the chamber 10 and thereby causing the valve 51 to close.
Since the movement of the valve 20 is controlled independently of the movement of the reciprocating piston 31, it is possible to open and/or close the communicating link between the pressure chamber 10 and the supply chamber 5 at any particular point during the upward stroke of the piston 31. Therefore, it can now readily be appreciated that the injection of fuel into the engine may be controlled by the electromagnetically operated valve 20 which in turn is controlled independently of the reciprocating piston 31. Therefore, the quantity of fuel injected into the engine is a function of the interval of time between the opening and closing of the relief passage 3 by the movement of valve 20.
In other words, when the relief port is closed (no communicating link between pressure chamber 10 and supply chamber 5), the piston 31 will pressurize fuel in the chamber 10 causing it to open injection valve 51 and inject fuel into the engine. However, at any time during this cycle the independently controlled valve 20 can be moved into a position that will establish a communicating link between the pressure chamber 10 and the supply chamber 5, thereby relieving the pressure in chamber 10 resulting in the closing of the injector or delivery valve 51.
While a preferred embodiment of the invention has been disclosed, it will be apparent to those skilled in the art that changes may be made to the invention as set forth in the appended claims, and in some cases certain features of the invention may be used to advantage without corresponding use of other features. Accordingly, it is intended that the illustrative and descriptive materials herein be used to illustrate the principles of the invention and not to limit the scope thereof.
This invention relates to an internal combustion engine fuel injection system of the type having a source of fuel, a fuel pump for pressurizing the fuel, and one or more injectors or nozzle assemblies for injecting fuel into the engine cylinders. The invention is more particularly related to an improved pump of the type having a reciprocating piston for pressurizing fluid and a solenoid-operated control valve for controlling the amount of fluid dispensed by the pump.
Mechanical fuel injection systems for internal combustion engines generally include a fuel tank; the fuel pump that receives fuel from the tank and pressurizes the fuel; and one or more nozzle valve assemblies that receive the pressurized fuel and inject it into the engine cylinder. The fuel pump which pressurizes the fuel to be supplied to the engine cylinders may be of the rotary or reciprocating piston or plunger type. An example of a rotary injection fuel pump may be found in U.S. Pat. No. 3,489,091 entitled "Rotary Distributor Pump," issued Jan. 13, 1970 to P. Becker. Examples of fuel injection pumps that operate on the principle of a reciprocating piston or plunger may be found in U.S. Pat. Nos. 2,922,581 entitled "Fuel Injection Apparatus", issued Jan. 26, 1960 to L. J. Garday; 3,146,715 entitled "Fuel Injection Pump," issued Sept. 1, 1964 to G. J. Knudson; and 3,190,561 entitled "Fuel Injector," issued June 22, 1965 to H. I. Fuller et al.
Fuel pumps of the reciprocating piston type generally include a housing; a piston mounted for reciprocating movement within the housing, the piston cooperatively linked to the crankshaft or camshaft of an internal combustion engine so that rotation of the camshaft causes reciprocation of the piston within the pump housing; and a pressure chamber, one wall of which is the face of the reciprocating piston, the pressure chamber having an inlet port, a relief (bypass) port and an injection port. In all of the reciprocating type pumps the piston includes a passageway (generally a groove or passage in the piston) that periodically links the pressure chamber to the relief port during the stroke of the piston. The shape and arrangement of the passage and the piston are designed so that radial adjustment of the piston (by rotating the piston) from one position to another affects the periodic linking of the relief port to the pressure chamber, thereby controlling injection time and hence the volume of fuel injected into an engine cylinder. Therefore, the quantity of fuel injected into the engine is determined by radially adjusting (rotating) the reciprocating pistons which are mechanically linked to the camshaft of the engine. Because the piston is mechanically linked to the camshaft, the point in time at which fuel is injected into the engine cylinders is generally fixed with respect to the degree of rotation of the camshaft from a common reference point.
Another limitation and disadvantage associated with fuel pumps of the reciprocating piston type is that the reciprocating piston determines the beginning of the injection cycle, i.e., the piston starts the beginning of the injection cycle when it closes the inlet port and the piston begins to build up pressure in the pressure chamber until the pressure reaches a point that causes the injection port to be opened and fuel to be injected into the engine cylinder. In most systems, once a reciprocating fuel pump is installed, the reciprocating piston is mechanically linked to the engine camshaft or crankshaft so that the inlet port always closes when the camshaft reaches the same degree of rotation. A common approach of making the closing of the inlet port vary with respect to the degree of rotation of the camshaft is to introduce a mechanical translator between the engine camshaft and the pump piston. However, mechanical translators (timing advance mechanisms) are both bulky and expensive, which of course is undesirable for commercial fuel injection systems. Another solution to the problem was to eliminate the reciprocating piston and employ a solenoid-operated injector which is electronically controlled by sophisticated switching circuitry. However, this type of system requires an extremely high pressure pump, more expensive electromechanical and electrical components, and very complex injectors.
Therefore, to control the amount of fuel injected into an internal combustion engine over a wide range of engine speeds, inventors have attempted to modify the fuel pump of the reciprocating piston type in a manner so as to control the inlet port opening and closing. Having failed to do this in an economical and practical way, the art has turned toward electronic fuel injection systems which do not employ a fuel pump of the reciprocating piston type and which are relatively expensive and complex.
SUMMARY OF THE INVENTION
This invention provides a mechanical fuel injection control system that utilizes a reciprocating piston type fuel pump that is capable of varying the amount of fuel injected into the engine cylinder at fixed and/or at different speeds of rotation of the engine cam and/or crank-shaft.
The invention is a fuel injection pump for an internal combustion engine characterized by an electromechanically operated control or relief valve assembly (27) that is controlled independently of a reciprocating piston (31) in the pump that pressurizes the fluid. The invention is also characterized by an electromechanical relief (control) valve (20) that has a valve face (23) that is not subject to the pressure in a pressure chamber so that the valve requires less electromechanical energy to open and close.
In one embodiment of the invention the fuel injection system for an internal combustion engine of the type having a camshaft comprises: a pump housing (1) having a pressure chamber (10) that communicates with an inlet passage (6), a relief passage (3) and an injection passage (15), the injection passage communicating with the engine; means for supplying fuel to the pumping chamber through said inlet passage; means for closing the injection passage (15), the closing means including biasing means (52), for keeping the injection passage closed until a predetermined fuel pressure is attained in the pumping chamber; means (30) responsive to the rotation of the engine camshaft or crankshaft for periodically pressurizing the fuel in the chamber (10) whereby fuel entering the chamber through the inlet passage periodically flows out of the pumping chamber through the relief (bypass) passage; and electro-mechanical valves means (27) operative to open and close the relief passage (3) at predetermined intervals in response to at least one operating parameter of the engine whereby each time the relief (bypass) passage (3) is closed and fuel is being pressurized, the fuel pressure in the pumping chamber attains a predetermined pressure level at which the injection passage is opened, thereby injecting fuel into the engine. This type of pump assembly makes it possible to open and close the relief passage independently of the reciprocating motion of the plunger 31.
Accordingly, it is an object of this invention to provide a fuel injection pump of a reciprocating piston type wherein the control of the relief valve is independent of the reciprocating piston.
It is another object of this invention to provide a control valve assembly for the relief (bypass) port of the pressure chamber wherein the axial movement of the valve is not biased by pressurized fluid within the pumping chamber.
It is still another object of this invention to eliminate the need for bulky and expensive mechanical timing devices between an internal combustion engine and a fuel injection pump.
It is yet another object of this invention to provide a control valve for a pressure chamber that permits a maximum flow rate to be obtained over a minimum amount of valve travel.
It is still another object of this invention to combine a novel means to control the amount and duration of fuel delivery with a fuel pump of known characteristics, thereby improving the versatility of fuel injector pumps of the reciprocating piston type.
It is also an object of this invention to provide a means for controlling fuel quantity and timing by utilizing a solenoid-operated control valve responding to one or more engine parameters.
The above and other objects and features of the invention wlll become apparent from the following detailed description taken in conjunction with the accompanying drawings and claims which form a part of this specification.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a fuel pump for an internal combustion engine that incorporates the principles of this invention.
FIG. 2 is an enlarged partial diagrammatic view showing the valve portion of the solenoid and the reciprocating plunger.
FIG. 3 is a diagrammatic top view of the pressure chamber taken along lines III--III in FIG. 2.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to the drawings, FIG. 1 illustrates a fuel injection pump 1 of the type having a reciprocating piston assembly 30 for pressurizing the fuel in response to rotation of an internal combustion engine (not shown), a solenoid-operated relief or control valve assembly 27 that is controlled independently of the reciprocating piston assembly 30, and an injection or delivery valve assembly 50 that communicates with the engine cylinder.
The reciprocating piston assembly 30 comprises: a can follower 32 that follows the camshaft or crankshaft of an internal combustion engine (not shown); a spring assembly 33 which maintains the cam follower 32 in contact with the camshaft; and a piston 31 which reciprocates in the bore of housing 60.
The electromegnetic valve assembly 27 comprises: a coil of wire 24 which receives power from a source (not shown); and a valve or solenoid core 20 which is axially movable in response to energization of the coil 24. Spring 28 biases valve 20 axially in the open position so that energization of the solenoid coil 24 is required to close the valve 20. The movable valve 20 includes a hollow portion 21, the purpose of which is to decrease the mass of the core so that less electromagnetic energy is required to move the valve 20. The valve 20 includes an end face 23 which terminates within the housing 60. An important feature of the valve 20 is the annular groove 2 therein which links relief passage 3 with the bore 10 in the housing 60 when the valve 20 is extended to its farthest position from the coil 24. Obviously, portions of the core 20 not required to be responsive to the solenoid can be fabricated from materials other than iron.
The pump assembly 1 further includes a source or supply chamber 5 which supplies fuel to a pressure chamber 10 through (inlet) passage 6. The supply chamber 5 also communicates with the pressure chamber 10 through (relief) passage 3 and the passage formed by the annular groove 2 of the valve 20 when the valve 20 is in the position shown.
In the FIGURE shown, passage 6 is closed because of the position of piston 31 and the relief passage 3 is open because of the position of the solenoid valve 20. Therefore, the inlet passage 6 of the pressure chamber 10 is closed and the relief passage 3 is open, preventing pressurizing of the fuel in chamber 10 by the piston 31.
The fuel injection pump 1 further includes an injection valve assembly 50 which includes: a delivery valve 51; a valve seat 49 for receiving valve 51; a spring assembly 52 for maintaining the valve 51 in a closed position until a predetermined pressure is attained in chamber 10, the valve 51 and valve seat 49 being disposed in a chamber 15 that communicates with passages 56 and 57 that lead to the engine cylinder. The valve 51 is shown in the closed position which prevents fuel in pressure chamber 10 from communicating with the fluid in chamber 15 and thereby injecting fuel into the engine. The valve 51 is biased closed by spring 52 so that valve 51 does not open until the pressure in the passage 10 reaches a predetermined pressure level which is much greater than any pressure level of the fluid in the supply chamber 5. FIG. 1 illustrates the pressurizing piston 31 at the top of its stroke and the solenoid valve positioned so that the pumping chamber 10 communicates with the supply chamber 5 through passage 3 so that the pressure in chamber 10 is not appreciably greater than the pressure within the supply chamber 5.
FIG. 2 is an enlarged cross-sectional diagrammatic view of the pump assembly shown in FIG. 1. In this diagrammatic view the supply chamber 5 communicates with the pressure chamber 10 only through the inlet passage 6 because the iron core 20 of the solenoid valve has been moved to a position to block the relief passage 3 that would otherwise communicate with the pressure chamber 10. This diagrammatic view illustrates that as piston 31 rises to point A, it closes the inlet port connected to the supply chamber 5, thereby allowing the fuel in the chamber 10 to be pressurized as the volume of the chamber decreases. When the pressure of the fluid in chamber 10 reaches a predetermined pressure value, valve 51 (FIG. 1) opens, allowing fluid to flow around the valve body 20 through the injector valve assembly (50, FIG. 1) and to the internal combustion engine (not shown). Another feature of the invention which can be seen in FIG. 2 is the fact that the face 23 of the valve 20 is not subject to the pressure in chamber 10. If the electromagnetic valve face 23 terminated within chamber 10, it would be subject to pressures that would require additional electromagnetic force to move the valve body 20. Further, since the movement of the valve 20 is independent of the operation of the reciprocating piston 31, control and injection of fuel into an engine cylinder may be started and stopped at any point in time regardless of the angle of rotation of the camshaft. This is an important feature of this invention in that prior art reciprocating type fuel injection pumps were not capable of obtaining this feature.
FIG. 3 is a diagrammatic view looking into pressure chamber 10 along lines III--III in FIG. 2. This FIGURE illustrates the shape of the pressure chamber 10 that allows pressurized fluid to flow around the valve body 20. The valve body 20 is shown in the open position so that fluid in the pressure chamber 10 may flow through the bypass or relief passage 3 to the supply chamber 5. This view further illustrates how axial movement of the valve 20 in an axial direction opens and closes the communicating link between the pressure chamber 10 and the bypass passage 3. This FIGURE further illustrates that the face of the valve 20 is not at any time located within the pressure chamber 10 and therefore is not subjected to any axial forces caused by the fluid in the chamber when the valve 20 is closed or open. Movement of the body 20 in either axial direction is in the order of .005 inches or less, allowing a maximum flow rate to be obtained in a minimum amount of time.
OPERATION
Referring now to the drawings, and more particularly to FIGS. 1 and 2, the fuel pump 1 operates as follows: a sensing device (not shown) senses one of the operating parameters of the internal combustion engine (not shown) to control the axial movement of the solenoid core or valve 20. The control signal has the effect of causing the body 20 to oscillate at various magnitudes and/or frequencies. Simultaneously with the movement of the iron core 20, the piston 31 reciprocates in response to the action of the spring 33 and cam follower 32 which is following the rotating camshaft of the internal combustion engine. Once the piston 31 has risen to a point in the bore of the housing 60 past the passage 6, fluid in the chamber 10 will or will not be pressurized, depending upon the location of the iron core 20. If the iron core 20 is in the position shown in FIG. 2, there is no communicating link between the chamber 10 and the supply chamber 5, as the location of annular groove 22 is such that passageway 3 does not communicate with pressure chamber 10. Therefore, pressure in the chamber 10 will increase until the delivery valve 51 opens, allowing fuel to pass through passage 57 and to the engine cylinder. Fuel will continue to flow through passage 57 until either the relief port opens or the piston 31 reverses direction, which increases the volume of chamber 10, decreasing the pressure in the chamber 10 and thereby causing the valve 51 to close.
Since the movement of the valve 20 is controlled independently of the movement of the reciprocating piston 31, it is possible to open and/or close the communicating link between the pressure chamber 10 and the supply chamber 5 at any particular point during the upward stroke of the piston 31. Therefore, it can now readily be appreciated that the injection of fuel into the engine may be controlled by the electromagnetically operated valve 20 which in turn is controlled independently of the reciprocating piston 31. Therefore, the quantity of fuel injected into the engine is a function of the interval of time between the opening and closing of the relief passage 3 by the movement of valve 20.
In other words, when the relief port is closed (no communicating link between pressure chamber 10 and supply chamber 5), the piston 31 will pressurize fuel in the chamber 10 causing it to open injection valve 51 and inject fuel into the engine. However, at any time during this cycle the independently controlled valve 20 can be moved into a position that will establish a communicating link between the pressure chamber 10 and the supply chamber 5, thereby relieving the pressure in chamber 10 resulting in the closing of the injector or delivery valve 51.
While a preferred embodiment of the invention has been disclosed, it will be apparent to those skilled in the art that changes may be made to the invention as set forth in the appended claims, and in some cases certain features of the invention may be used to advantage without corresponding use of other features. Accordingly, it is intended that the illustrative and descriptive materials herein be used to illustrate the principles of the invention and not to limit the scope thereof.